ruby-graphql-server-example

An example GraphQL server implementation in Ruby

This project uses Sinatra, Sequel and the graphql-ruby gem to create a Postgres-backed GraphQL server in Ruby. It implements the HTTP protocol outlined in the GraphQL HTTP best practices.

You can try it out on Heroku.

Requirements
Installation
Usage
Data model
Example queries
GraphiQL
Development

Requirements

Installation

bundle install

Usage

Setup a local database:

bundle exec rake db:migrate

Add some seed data:

bundle exec rake db:seed

Start the server:

bundle exec ruby app.rb

This will start a server running with a GraphQL endpoint at http://localhost:4567/graphql and the GraphiQL tool at http://localhost:4567.

Data model

The data model represents a simple video-on-demand service that displays shows, seasons and episodes.

type Show {
  id: ID!
  title: String!
  seasons: [Season]!
  episodes: [Episode]!
}

type Season {
  id: ID!
  title: String!
  number: Int!
  episodes: [Episode]!
}

type Episode {
  id: ID!
  title: String!
  number: Int!
  show: Show!
  season: Season!
}

Example queries

Let's create a simple GraphQL query in a query.graphql file that returns all of the shows:

{
  shows {
    id
    title
  }
}

We can run that query against the server using curl:

curl -X POST http://localhost:4567/graphql \
  -H 'Content-Type: application/graphql' \
  -d @query.graphql | jq .

Here we're using jq (brew install jq) to get a pretty-printed JSON output

The output of the curl command will look like:

{
  "data": {
    "shows": [
      {
        "id": "b013pqnm",
        "title": "The Great British Bake-Off"
      },
      {
        "id": "b0071b63",
        "title": "The Apprentice"
      },
      {
        "id": "b062r9t5",
        "title": "People Just Do Nothing"
      }
    ]
  }
}

We can then modify the query to return the nested episodes in each show:

{
  shows {
    id
    title
    episodes {
      id
      number
      title
    }
  }
}

Which returns:

{
  "data": {
    "shows": [
      {
        "id": "b013pqnm",
        "title": "The Great British Bake-Off",
        "episodes": [
          {
            "id": "b07r246c",
            "number": 1,
            "title": "Cake Week"
          },
          {
            "id": "b07tj10j",
            "number": 2,
            "title": "Biscuit Week"
          },
          {
            "id": "b07v324h",
            "number": 3,
            "title": "Bread Week"
          }
        ]
      },
      {
        "id": "b0071b63",
        "title": "The Apprentice",
        "episodes": [
          {
            "id": "b07ynzyc",
            "number": 1,
            "title": "Collectables"
          },
          {
            "id": "b07zfh1b",
            "number": 2,
            "title": "Advertising - Jeans"
          },
          {
            "id": "b0806vqc",
            "number": 3,
            "title": "Corporate Candy"
          }
        ]
      },
      {
        "id": "b062r9t5",
        "title": "People Just Do Nothing",
        "episodes": [
          {
            "id": "p043m903",
            "number": 1,
            "title": "Dubplate"
          },
          {
            "id": "b07tl80w",
            "number": 2,
            "title": "Record Deal"
          },
          {
            "id": "p045280q",
            "number": 3,
            "title": "Court Case"
          }
        ]
      }
    ]
  }
}

We can use arguments on the episodes field to return only the latest episode in each show:

{
  shows {
    id
    title
    episodes(limit: 1, sortDirection: DESC) {
      id
      number
      title
    }
  }
}

{
  "data": {
    "shows": [
      {
        "id": "b013pqnm",
        "title": "The Great British Bake-Off",
        "episodes": [
          {
            "id": "b07v324h",
            "number": 3,
            "title": "Bread Week"
          }
        ]
      },
      {
        "id": "b0071b63",
        "title": "The Apprentice",
        "episodes": [
          {
            "id": "b0806vqc",
            "number": 3,
            "title": "Corporate Candy"
          }
        ]
      },
      {
        "id": "b062r9t5",
        "title": "People Just Do Nothing",
        "episodes": [
          {
            "id": "p045280q",
            "number": 3,
            "title": "Court Case"
          }
        ]
      }
    ]
  }
}

We can query for a particular show:

{
  show(id: "b013pqnm") {
    id
    title
  }
}

{
  "data": {
    "show": {
      "id": "b013pqnm",
      "title": "The Great British Bake-Off"
    }
  }
}

And then retrieve its entire hierarchy, including seasons and episodes:

{
  show(id: "b013pqnm") {
    id
    title,
    seasons {
      id
      title
      number
      episodes {
        id
        title
        number
      }
    }
  }
}

{
  "data": {
    "show": {
      "id": "b013pqnm",
      "title": "The Great British Bake-Off",
      "seasons": [
        {
          "id": "b07r2pr0",
          "title": "Series 7",
          "number": 7,
          "episodes": [
            {
              "id": "b07r246c",
              "title": "Cake Week",
              "number": 1
            },
            {
              "id": "b07tj10j",
              "title": "Biscuit Week",
              "number": 2
            },
            {
              "id": "b07v324h",
              "title": "Bread Week",
              "number": 3
            }
          ]
        }
      ]
    }
  }
}

We can also a retrieve an episode by its ID:

{
  episode(id: "p043m903") {
    id
    number
    title
  }
}

{
  "data": {
    "episode": {
      "id": "p043m903",
      "number": 1,
      "title": "Dubplate"
    }
  }
}

And return its season and show:

{
  episode(id: "p043m903") {
    id
    number
    title
    season {
      id
      title
    }
    show {
      id
      title
    }
  }
}

{
  "data": {
    "episode": {
      "id": "p043m903",
      "number": 1,
      "title": "Dubplate",
      "season": {
        "id": "p043m8g0",
        "title": "Series 3"
      },
      "show": {
        "id": "b062r9t5",
        "title": "People Just Do Nothing"
      }
    }
  }
}

GraphiQL

The server includes the GraphiQL tool.

You can use it to explore the API in your browser by visiting http://localhost:4567/.

The GraphiQL installation follows the official example.

Development

To use Shotgun to reload the server in development:

bundle exec shotgun

All SQL queries are logged by default in development. This is disabled when the RACK_ENV environment variable is missing or set to production.

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